package 数据结构.映射.二分搜索树映射;

import 数据结构.映射.Map;

/**
 * @author Veng Su 1344114844@qq.com
 * @date 2018/7/24 10:13
 */
public class BSTMap<K extends Comparable<K>,V> implements Map<K,V> {
    private class Node {
        public K key;
        public V value;
        Node left, right;

        public Node(K key,V value) {
            this.key=key;
            this.value=value;
            left = null;
            right = null;
        }
    }
    private Node root;
    private int size;
    public BSTMap(){
        this.root=null;
        this.size=0;
    }
    private Node getNode(Node node,K key){
        if (node==null){
            return null;
        }
        if (key.compareTo(node.key)==0){
            return node;
        }else if(key.compareTo(node.key)<0){
            return getNode(node.left,key);
        }else {
            return getNode(node.right,key);
        }

    }
    @Override
    public void add(K key, V value) {
        root=add(root,key,value);
    }

    private Node add(Node node, K key, V value) {
        if (node==null){
            size++;
            return new Node(key,value);
        }
        if (key.compareTo(node.key)<0){
            node.left=add(node.left,key,value);
        }else if (key.compareTo(node.key)>0){
            node.right=add(node.right,key,value);
        }else {
            node.value=value;
        }
        return node;
    }

    @Override
    public V remove(K key) {
        Node node =getNode(root,key);
        if (node!=null){
            root=remove(root,key);
            return node.value;
        }
        return null;
    }

    private Node remove(Node node, K key) {
        if (node == null) {
            return node;
        }
        if (key.compareTo(node.key) < 0) {
            node.left = remove(node.left, key);
            return node;
        } else if (key.compareTo(node.key) > 0) {
            node.right = remove(node.right, key);
            return node;
        } else {
            if (node.left == null) {
                Node rightNode = node.right;
                node.right = null;
                size--;
                return rightNode;
            }
            if (node.right == null) {
                Node leftNode = node.left;
                node.left = null;
                size--;
                return leftNode;
            }
            Node sucessor = minium(node.right);
            sucessor.right = removeMin(node.right);
            sucessor.left = node.left;
            node.left = null;
            node.right = null;
            return sucessor;
        }
    }
    private Node minium(Node node) {
        if (node.left == null) {
            return node;
        } else {
            return minium(node.left);
        }
    }

    private Node removeMin(Node node) {
        if (node.left == null) {
            Node rightNode = node.right;
            node.right = null;
            size--;
            return rightNode;
        }
        node.left = removeMin(node.left);
        return node;
    }

    @Override
    public boolean contains(K key) {
        return getNode(root,key)!=null;
    }

    @Override
    public V get(K key) {
        Node node=getNode(root,key);
        return node==null?null:node.value;
    }

    @Override
    public void set(K key, V newValue) {
        Node node=getNode(root,key);
        if (node==null){
            throw new IllegalArgumentException("key 不存在");
        }
        node.value=newValue;
    }

    @Override
    public int getSize() {
        return size;
    }

    @Override
    public boolean isEmpty() {
        return size==0;
    }
}
